Mr. Trump also applies makeup to a bruise on the back of his right hand, adding speculation about a medical condition that his physician and aides say is caused by taking aspirin and shaking so many hands. In September, the bruising on his hand, coupled with swollen ankles, caused observers on the internet to speculate wildly about his health.

In response to a list of questions about Mr. Trump’s health, including about the results of his M.R.I. and whether or not he was falling asleep in the Oval Office, Karoline Leavitt, the White House press secretary, praised the president’s energy and pointed to Mr. Biden.